1
An introduction to radiation hard
Monolithic Active Pixel Sensors Or:
A tool to measure Secondary Vertices
Dennis Doering*, Goethe University Frankfurt am Main
on behalf of the CBM-MVD-Collaboration
2
Outline- The challenge to measure Secondary Vertices- Operation principle of MAPS- Radiation damage effects- High Resistivity and radiation hardness- Conclusion
An introduction to radiation hard
Monolithic Active Pixel Sensors Or:
A tool to measure Secondary Vertices
/17/25
Task: Reconstruct Secondary Vertices
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 3
Primary Beam: 25 AGeV Au Ions (up to 109/s)
Reconstruction concept for open charm
/17/25
Task: Reconstruct Secondary Vertices
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 4
Primary Beam: 25 AGeV Au Ions (up to 109/s)
Primaryvertex
Target(Gold)
Reconstruction concept for open charm
/17/25
Task: Reconstruct Secondary Vertices
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 5
Primary Beam: 25 AGeV Au Ions (up to 109/s)
Primaryvertex
Target(Gold)
Reconstruction concept for open charm
/17/25
Task: Reconstruct Secondary Vertices
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 6
Primary Beam: 25 AGeV Au Ions (up to 109/s)
Primaryvertex Secondary
vertexShort lived particle D0 (ct = ~ 120 µm)
Target(Gold)
Reconstruction concept for open charm
/17/25
Task: Reconstruct Secondary Vertices
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 7
Primary Beam: 25 AGeV Au Ions (up to 109/s)
Primaryvertex Secondary
vertexShort lived particle D0 (ct = ~ 120 µm)
Detector 1Detector2Target
(Gold)
z
Reconstruction concept for open charm
z= 5cm
/17/25
Task: Reconstruct Secondary Vertices
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 8
Primary Beam: 25 AGeV Au Ions (up to 109/s)
Primaryvertex Secondary
vertexShort lived particle D0 (ct = ~ 120 µm)
Detector 1Detector2Target
(Gold)
z= 5cm
Reconstruction concept for open charm
1) Short life time:
- Good spatial resolution- low material budget (scattering)
2) Rare probe-> High statistics
- Fast - Radiation hard
/17/25
Task: Reconstruct Secondary Vertices
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 9
Primary Beam: 25 AGeV Au Ions (up to 109/s)
Primaryvertex Secondary
vertexShort lived particle D0 (ct = ~ 120 µm)
Detector 1Detector2Target
(Gold)
z
Reconstruction concept for open charm
1) Short life time:
- Good spatial resolution- low material budget (scattering)
2) Rare probe-> High statistics
- Fast - Radiation hard
Is it possible to develop such a detector?Þ MAPS in CBM @ FAIR
z= 5cm
/17/25
Use digital cameras as particle detector
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 10
Primary Beam: 25 AGeV Au Ions (up to 109/s)
Primaryvertex Secondary
vertexShort lived particle D0 (ct = ~ 120 µm)
Detector 1Detector2Target
(Gold)
z
Reconstruction concept for open charm
1) Short life time:
- Good spatial resolution- low material budget (scattering)
2) Rare probe-> High statistics
- Fast - Radiation hard
Is it possible to develop such a detector?Þ MAPS in CBM @ FAIR
z= 5cm
/17/25
Use digital cameras as particle detector: MAPS
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 11
Primary Beam: 25 AGeV Au Ions (up to 109/s)
Primaryvertex Secondary
vertexShort lived particle D0 (ct = ~ 120 µm)
Detector 1Detector2Target
(Gold)
z
Reconstruction concept for open charm
1) Short life time:
- Good spatial resolution- low material budget (scattering)
2) Rare probe-> High statistics
- Fast - Radiation hard
Is it possible to develop such a detector?Þ MAPS in CBM @ FAIR
z= 5cm
/17/25
Operation principle
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 12
SiO2 SiO2 SiO2
N+ P+
P-
P+
Diode
Epitaxial Layer
P-Well
Substrate
e-
N+
e-
Particle
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Operation principle
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 13
SiO2 SiO2 SiO2
N+ P+
P-
P+
Diode
Epitaxial Layer
P-Well
Substrate
N+ 50µm
Thin and good spatial resolution
10-40µm => a few µm resolution
/17/25
Operation principle
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 14
SiO2 SiO2 SiO2
N+ P+
P-
P+
Diode
Epitaxial Layer
P-Well
Substrate
N+
10-40µm => a few µm resolution
50µm
Compare HADES MWPC:Drift cell „pitch“: few 1000µmResolution: few 100µm
/17/25
Radiation hardness?
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 15
Reconstruct up to 1000 tracks per collision and 1010 collisions per year
Fast readout and radiation hardness up to ~1013neq/cm² and ~1 MRad
Central Au + Au collision (25 AGeV)
/17/25Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 16
Classes of radiation damageTo be investigated and improved: Radiation hardness against…
… ionizing radiation:• Caused by charged particles and photons • Can ionize atoms and destroy molecules
… non-ionizing radiation:• Caused by heavy, charged and neutral,
particles• Atoms are displaced
Farnan I, HM Cho, WJ Weber, 2007. "Quantification of Actinide α-Radiation Damage in Minerals and Ceramics." Nature 445(7124):190-193.
/17/25
Non-ionizing radiation (Low Resistivity)
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 17
SiO2 SiO2
SiO2
N+ P+
P-
P+
Diode
Epitaxial Layer
P-Well
Substrate
N+
Defects generated by non-ionizing radiation.
e-
/17/25
The history of radiation hard MAPS
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 18
0 5 10 15 20 25 30 35 401011
1012
1013
1014
1015
Mimosa9 (2004)
Mimosa9 (2004)
Mimosa15 (2006)Mimosa18 (2008)
Low resistivity sensors Uncertainty range
Rad
iatio
n to
lera
nce
[neq
/cm
²]
Pixel pitch [µm]
Smaller pixel pitch => better radiation hardness
/17/25
High Resistivity
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 19
SiO2 SiO2
SiO2
N+ P+
P-
P+
Diode
Epitaxial Layer
P-Well
Substrate
N+
e-depletion
/17/25
Non-ionizing radiation (High resistivity)
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 20
SiO2 SiO2
SiO2
N+ P+
P-
P+
Diode
Epitaxial Layer
P-Well
Substrate
N+
depletion e-
/17/25
The history of radiation hard MAPS
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 21
0 5 10 15 20 25 30 35 401011
1012
1013
1014
1015
Mimosa9
Mimosa9
Mimosa15 (2006)Mimosa18 (2008)
Mimosa18 AHR (2011)
High resistivity sensors Low resistivity sensors Uncertainty range
Rad
iatio
n to
lera
nce
[neq
/cm
²]
Pixel pitch [µm]
Mimosa26 AHR (2010)
/17/25
Beam test @ CERN by IPHC Strasbourg
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 22
4 5 6 7 8 9 10 11 1293
94
95
96
97
98
99
100
Low Resistivity no irradiation High Resistivity no irradiation High Resistivity 1013n
eq/cm²E
ffici
ency
[%]
Threshold [mV]
Irradiated High Resistivity sensor: Better efficiency than unirradiated Low Resistivity sensor.
Threshold
Signal
Noise
/17/25
10
20
30
40
50
60
-34-27-15
Noi
se [e
]
Temperature [°C]-3
10
20
30
40
50
60
-34-27-15
Noi
se [e
]
Temperature [°C]-3
Noise increases
Sensor: - Mi-18 AHR, SB-Pixel, 10 µm pitch - Epitaxial layer: 400 W cm, 15 µm Irradiation: - fast reactor neutrons (Triga, Ljubljana) - Chip not powered during irradiation - Dose: 3 · 1014neq/cm² + O(3 MRad)
0 50 100 150 200 250 300 350 4000
1000200030004000500060007000
Ent
ries
[1 b
in=4
AD
C]
Charge collected [ADC]
<20% less entriesThinner active vol.?
CCE ok
Gain okFe-55 (X-rays)
0 500 1000 1500 2000 2500 3000 35000
500
1000
1500
2000
2500
3000
3500
Ent
ries
[1 b
in=4
AD
C]
Charge collected [e]
Ru-106 (b-rays)
99% det. eff.after irrad.
620e (MPV)
490e (MPV) <20% less signalThinner act. vol.?
Noise increases =>Compensate with cooling.
3 · 1014neq/cm² + O(3 MRad)Not irradiated
Limit of radiation hardness?
23Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 Preliminary conclusion: Sensor tolerates 3 · 1014neq/cm², to be confirmed in beam test
/17/25
- Forseen in ILC, STAR, CBM and ALICE- MAPS are the technology of choice for Open Charm in CBM- Requirements today not fully fulfilled, however ongoing research- Great improvements in the last few years and many ideas for future- Demonstrated excellent performance in beam test, even after 1013 neq/cm²- Sensor operational in laboratory even after 3·1014neq/cm²
Summary
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 24
/17/25
- Forseen in ILC, STAR, CBM and ALICE- MAPS are the technology of choice for Open Charm in CBM- Requirements today not fully fulfilled, however ongoing research- Great improvements in the last few years and many ideas for future- Demonstrated excellent performance in beam test, even after 1013 neq/cm²- Sensor operational in laboratory even after 3·1014neq/cm²
Summary
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 25
Conclusion: Monolithic Active Pixel Sensors A detector that YOU should know
/17/25Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 26
BACK-UP
/17/25
Column parallel sensors
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 27
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Column parallel sensors
Dennis Doering: An introduction to MAPS Hades Summer School Prague Oct. 2011 28
Readout speed achieved: <100µsDesign goal for >2015: 30µsMaybe possible in future: <5µs
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